From caf1c31c25349d29011d5772bba7eb2709879eb5 Mon Sep 17 00:00:00 2001
From: Jakob Hellermann <jakob.hellermann@protonmail.com>
Date: Thu, 21 Jan 2021 16:46:28 +0100
Subject: [PATCH] add ReflectedUI wrapper type for implementing Inspectable
 based on Reflect

---
 examples/reflect.rs |  25 ++++++++
 src/lib.rs          |   3 +
 src/reflect/mod.rs  | 143 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 171 insertions(+)
 create mode 100644 examples/reflect.rs
 create mode 100644 src/reflect/mod.rs

diff --git a/examples/reflect.rs b/examples/reflect.rs
new file mode 100644
index 00000000..9577ba33
--- /dev/null
+++ b/examples/reflect.rs
@@ -0,0 +1,25 @@
+use bevy::prelude::*;
+use bevy_inspector_egui::{reflect::ReflectedUI, Inspectable, InspectorPlugin};
+
+#[derive(Inspectable, Default, Debug)]
+struct Data {
+    // it works for custom reflect types
+    custom: ReflectedUI<MyComponent>,
+    // also for builtin implementations
+    color: ReflectedUI<Color>,
+    // and for most of bevy's types
+    timer: ReflectedUI<Timer>,
+}
+
+#[derive(Reflect, Default, Debug)]
+struct MyComponent {
+    a: f32,
+    b: Vec2,
+}
+
+fn main() {
+    App::build()
+        .add_plugins(DefaultPlugins)
+        .add_plugin(InspectorPlugin::<Data>::new())
+        .run();
+}
diff --git a/src/lib.rs b/src/lib.rs
index fbd646a7..b1c863f4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -41,6 +41,9 @@
 mod impls;
 mod plugin;
 
+/// `Inspectable` implementation for foreign types implementing `Reflect`
+pub mod reflect;
+
 pub use bevy_egui::egui;
 
 /// Derives the [`Inspectable`](Inspectable) trait.
diff --git a/src/reflect/mod.rs b/src/reflect/mod.rs
new file mode 100644
index 00000000..510ef6bb
--- /dev/null
+++ b/src/reflect/mod.rs
@@ -0,0 +1,143 @@
+use std::ops::{Deref, DerefMut};
+
+use bevy::prelude::*;
+use bevy::reflect::{List, Map};
+use bevy_egui::egui;
+use egui::Grid;
+
+use crate::Inspectable;
+
+/// Wrapper type for displaying inspector UI based on the types [`Reflect`](bevy::reflect::Reflect) implementation.
+///
+/// Say you wanted to display a type defined in another crate in the inspector, and that type implements `Reflect`.
+/// ```rust
+/// # use bevy::prelude::*;
+/// #[derive(Reflect, Default)]
+/// struct SomeComponent {
+///     a: f32,
+///     b: Vec2,
+/// }
+/// ```
+///
+/// Using the `ReflectedUI` wrapper type, you can include it in your inspector
+/// and edit the fields like you would expect:
+///
+/// ```rust
+/// # use bevy::prelude::*;
+/// # use bevy_inspector_egui::{Inspectable, reflect::ReflectedUI};
+/// # #[derive(Reflect, Default)] struct SomeComponent;
+/// #[derive(Inspectable, Default)]
+/// struct Data {
+///     component: ReflectedUI<SomeComponent>,
+///     // it also works for bevy's types
+///     timer: ReflectedUI<Timer>,
+/// }
+/// ```
+#[derive(Debug, Default)]
+pub struct ReflectedUI<T>(T);
+impl<T> ReflectedUI<T> {
+    pub fn new(val: T) -> Self {
+        ReflectedUI(val)
+    }
+}
+
+impl<T> Deref for ReflectedUI<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl<T> DerefMut for ReflectedUI<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl<T: Reflect> Inspectable for ReflectedUI<T> {
+    type Attributes = ();
+
+    fn ui(&mut self, ui: &mut egui::Ui, _: Self::Attributes) {
+        ui_for_reflect(&mut self.0, ui);
+    }
+}
+
+macro_rules! try_downcast_ui {
+    ($value:ident $ui:ident => $ty:ty) => {
+        if let Some(v) = $value.downcast_mut::<$ty>() {
+            <$ty as Inspectable>::ui(v, $ui, <$ty as Inspectable>::Attributes::default());
+            return;
+        }
+    };
+
+    ( $value:ident $ui:ident => $( $ty:ty ),+ $(,)? ) => {
+        $(try_downcast_ui!($value $ui => $ty);)*
+    };
+}
+
+fn ui_for_reflect(value: &mut dyn Reflect, ui: &mut egui::Ui) {
+    try_downcast_ui!(value ui => Color);
+
+    match value.reflect_mut() {
+        bevy::reflect::ReflectMut::Struct(s) => ui_for_reflect_struct(s, ui),
+        bevy::reflect::ReflectMut::TupleStruct(value) => ui_for_tuple_struct(value, ui),
+        bevy::reflect::ReflectMut::List(value) => ui_for_list(value, ui),
+        bevy::reflect::ReflectMut::Map(value) => ui_for_map(value, ui),
+        bevy::reflect::ReflectMut::Value(value) => ui_for_reflect_value(value, ui),
+    }
+}
+
+fn ui_for_reflect_struct(value: &mut dyn Struct, ui: &mut egui::Ui) {
+    ui.vertical_centered(|ui| {
+        let grid = Grid::new(value.type_id());
+        grid.show(ui, |ui| {
+            for i in 0..value.field_len() {
+                match value.name_at(i) {
+                    Some(name) => ui.label(name),
+                    None => ui.label("<missing>"),
+                };
+                if let Some(field) = value.field_at_mut(i) {
+                    ui_for_reflect(field, ui);
+                } else {
+                    ui.label("<missing>");
+                }
+                ui.end_row();
+            }
+        });
+    });
+}
+
+fn ui_for_tuple_struct(value: &mut dyn TupleStruct, ui: &mut egui::Ui) {
+    let grid = Grid::new(value.type_id());
+    grid.show(ui, |ui| {
+        for i in 0..value.field_len() {
+            ui.label(i.to_string());
+            if let Some(field) = value.field_mut(i) {
+                ui_for_reflect(field, ui);
+            } else {
+                ui.label("<missing>");
+            }
+            ui.end_row();
+        }
+    });
+}
+
+fn ui_for_list(_value: &mut dyn List, ui: &mut egui::Ui) {
+    ui.label("List not yet implemented");
+}
+
+fn ui_for_map(_value: &mut dyn Map, ui: &mut egui::Ui) {
+    ui.label("Map not yet implemented");
+}
+
+fn ui_for_reflect_value(value: &mut dyn Reflect, ui: &mut egui::Ui) {
+    try_downcast_ui!(
+        value ui =>
+        f32, f64, u8, u16, u32, u64, i8, i16, i32, i64,
+        String, bool,
+        Vec2, Vec3, Vec4, Mat3, Mat4,
+        Transform, Quat,
+    );
+
+    ui.label(format!("Not implemented: {}", value.type_name()));
+}